The present disclosure relates to a rotary milling cutter such as an end mill to be used for milling workpieces such as metals and the like to be rolled into tubing and other applications, and a milling method using the same.
Milling cutters are typically rotatable tools of cylindrical, conical, or disk form, having a plurality of cutting edges. Such cutters are available in many forms, such as plain cylindrical, side milling cutters, face and end mills, formed cutters, and standard and special shaped profile cutters. High speed steel cutters are used for short production runs and carbide cutters are often used for long runs. One form of a cutting insert is described in U.S. Pat. No. 5,685,670 hereby incorporated by reference. Similarly, for lathe tools, each cutting edge has a clearance angle which is always positive, and a rake angle which is often positive, but may be zero or negative, for example when the cutter tooth is made of a hard grade of tungsten carbide and machining is carried out at high speeds yet without a coolant. Also similar to lathe tools, the recommended relief angles depend on the material to be machined and the material of which the cutter is made.
Conventionally, in the field of milling of metals, a rotary milling cutter such as an end mill that performs milling by rotating about a rotation axis has been used for fabricating tubes or pipes from sheet metal. Such a rotary milling cutter is provided with a cutting edge at its distal portion or at a side of the distal portion, and is capable of milling by rotating about the rotation axis. An example of a conventional rotary milling cutter is shown in FIG. 1. When a metal block is milled to a predetermined depth, the size of each angle R coincides with the diameter of the cutter C.
A strip of material runs through the milling cutter to be rolled or formed into pipe or tubing. As such, the opposite edges need to be milled to have clean, precise edges. In current milling cutters, the mill contacts the strip and remains stationary. Rotary milling methods that use a conventional end mill have other problems as well. For example, existing end milling devices do not compensate for floating of a workpiece through the mill; thus, an equal amount of material is not removed from each end of the sheet. Accordingly, it is desired to provide an edge milling device which removes equal amounts of material from each edge, regardless of the amount of float of the sheet through the mill.